Bitcoin is not gambling it is just a digital money. Gambling is involve when someone uses bitcoin as a medium of exchange during the gambling process just like your fiat currency
Of course bitcoin is not a gambling, and you are correct since its is a cryptocurrency in specific terms. But when you buy it and hold, and expecting it to have a bigger value in the future, you are gambling here
Because when your target is not met, you lose. there is a risk here involved when you consider bitcoin as an asset.